In many industries, the system for fluid handling must be extremely sanitary and easily cleanable. For example, industries such as biological R&D, biological pilot plants and biological and food production facilities require steam-in-place (SIP) sterilization and clean-in-place (CIP) sanitization for process systems. Thus, valves used in these systems must have certain characteristics to be SIP/CIP capable. Specifically, these valves should be able to withstand the pressure of SIP/CIP procedures, should be completely drainable and should have product contact surfaces that do not yield byproducts that can leach into the process stream after SIP/CIP.
In the sanitary industries, the most prevalent type of valve used is the diaphragm valve. To date, diaphragm valve technology has been the only valve technology to develop multi-port or valve clusters that minimize dead leg. Historically these valves have been viewed as sanitary and easy to clean. However, diaphragm valves possess specific drawbacks that can be significantly improved upon for applications in the sanitary industries. One such universal limitation is that diaphragm valves do not provide a smooth, seamless passageway for fluid flow, as the diaphragms themselves have sealing points and fluid must travel up and around a weir.
Several diaphragm valves have been designed to be SIP/CIP capable and drainable to meet the requirements of sanitary processes. For example, in U.S. Pat. No. 6,672,561, Kerg et al. describe a radial diaphragm valve having an elongated stem with a circumferential recess that receives a seal whose function is to separate the process fluid from the interior of the actuator.
Though Kerg's valve is SIP/CIP capable and drainable, this valve is incapable of having multiple ports and does not possess a product contact area that is entirely disposable. Also, the seal in the elongated stem creates crevices that can potentially trap and harbor contaminants or can potentially leak.
Cordova (U.S. Pat. No. 6,672,566) and Kovacs et al (U.S. Pat. No. 6,237,637) provide diaphragm valves that have multiple ports and are SIP/CIP capable and drainable. Cordova provides a multi-use sterile access/GMP diaphragm valve housing block having a main flow axis and having a first port and an opposing second port extending to a first and second passage, respectively, separated by a main flow weir.
Kovacs' invention is a diverter valve casing that includes a body with a base and plurality of walls that cooperatively form a chamber, a partition within the chamber dividing the chamber into a plurality of compartments. The partition further includes a surface partially defining the first compartments that is partially sloped. Drawbacks to both the Cordova and Kovacs valves are that these inventions create large sealing areas that can be sites for contamination, and they do not offer an entirely disposable product contact area(s). In addition, Cordova's valve requires difficult installation, as the valve must be of a particular orientation to achieve proper drainage.
In U.S. Pat. No. 5,549,134, Browne et al. also provides a diaphragm valve that is drainable. Browne's sanitary valve is comprised of a valve body, a diaphragm and an actuator. The valve body features a cavity defined by the inventor as a “fluid chamber”, which has holes in the side and bottom of the cavity for passage of fluid. Passages connect the holes to ports outside the valve body. A diaphragm is mounted over the cavity, a raised area that controls fluid flow through the valve. Though this valve provides drainage, again the diaphragm creates a large seal to protect the contents of the valve from the outside and does not offer a product contact area that is completely disposable, limiting the sterility and easy cleaning of this invention.
Hoobyar et al (U.S. Pat. No. 5,152,500) also provides a drainable valve that is SIP/CIP capable. This sanitary bottom tank valve features one inlet flow passage to communicate flow into the valve body and to at least one outlet passage. An actuator is secured to the valve body to move a diaphragm in an open or closed position in relation to the inlet flow passageway. The main valve passage is typically mounted to the bottom of a tank, which does provide drainage. Hoobyar's valve is limited in its ability to be incorporated into a standard piping system. This valve also has the same shortcomings as those previously described, in that the diaphragm creates a large seal and the valve does not provide a completely disposable product contact area.
In U.S. Pat. No. 5,222,523 to Trimble, a valve comprised of a body defining a through passage, a branch passage and an aperture in the wall of the through passage. A diaphragm, which the inventor defines as a “closure member”, is movable between an open and closed position to establish communication between the through and branch passages. Trimble's valve is drainable and SIP/CIP capable. However, the diaphragm creates a large seal that is necessary to protect its fluid contents from the outside environment, and it does not provide a completely disposable product contact area.
In U.S. Pat. No. 4,259,985, Bergmann provides a three-way pinch valve operated by a solenoid with one pinch valve mounted on each end and constructed such that one valve is normally open while the other valve is normally closed. The valve is made three-way by connecting the tubing from the two pinch valves to a T-fitting with a single outlet. Bergmann's valve eliminates the sealing surfaces and weirs associated with the above diaphragm valve designs, but this valve is not SIP/CIP capable, and the three fluid channels cannot be engaged independently.
Valves used for sanitary fluid transfer must not contaminate the fluid product, nor allow internal or external sources of contamination to enter the process stream. Sources of contamination from inside the valve can include material from the valve itself or accumulated residue from cleaning that is entrapped in the valve. Sources of contamination from outside a valve include any material that can enter through seals or diaphragm sealing surfaces. Such sources include germs, viruses or microorganisms in fluids used to actuate the valve. To eliminate internal and external sources of contamination, it is necessary that the valve's product contact surfaces be noncontaminating and the valve body does not have sealing points.
To effectively eliminate contamination, valves for sanitary applications should have a smooth, reliable passageway that is completely drainable to prevent any entrapment of fluid material. In order to be compatible with the often complex configuration of fluid-handling systems, it is critical that the valve be small, simple and equipped with tubing elements that are easy to change out.
Valves used for sanitary fluid transfer should also be designed to minimize dead leg. A complete discussion of the phenomenon of dead leg can be found in the ASME/BPE Guidelines 1999, Part SD “Design for Sterility and Cleanability”; Part SG “Equipment Seals.”
There is a need in the industry for a pinch-type valve arrangement that overcomes the problems of multi-port diaphragm and pinch valves currently used in the sanitary industries. Specifically, there is a need for a valve arrangement that provides multiple smooth, seamless and reliable fluid pathways that are SIP/CIP capable, easily disposed of and fully drainable with the valve in any position.